1. Field of the Invention
The present invention relates to an imaging device.
Priority is claimed on Japanese Patent Application No. 2010-091350, filed Apr. 12, 2010, the content of which is incorporated herein by reference.
2. Description of Related Art
To finely detect spectral information of a subject, an imaging wavelength region must be divided into a greater number of fine channels. These pieces of spectral information of the divided channels are then combined to obtain spectral information of the subject. An imaging device that uses this method to acquire multispectral information of a subject is known in the related art (e.g. see Japanese Patent No. 4043662).
FIG. 13 is a block diagram of the configuration of a multispectral imaging device of the related art. In the example of FIG. 13, a multispectral imaging device 60 includes a liquid crystal tunable filter 61, an imaging element 62, a liquid crystal tunable filter controller 63, and an image processor 64. The liquid crystal tunable filter controller 63 controls the spectral transmissivity of the liquid crystal tunable filter 61 such that the liquid crystal tunable filter 61 transmits light of a wavelength that is of interest. Light of a wavelength that passed through the liquid crystal tunable filter 61 is imaged by the imaging element 62, and processed by the image processor 64, whereby the multispectral imaging device 60 acquires a multispectral image of the subject.
FIG. 14 is a graph of an example of spectral characteristics of the liquid crystal tunable filter 61 of the related art. As shown in FIG. 14, due to the control conducted by the liquid crystal tunable filter controller 63, the liquid crystal tunable filter 61 can transmit light of a wavelength that finely divides the imaging wavelength region.
Furthermore, as a method of acquiring multispectral information with a simpler device, a technique of using a miniature spectrometer fitted to an RGB camera to measure the spectrum of a subject at a great many points, and use that information to enhance the color reproducibility from an RGB image is known in the prior art (e.g. see Papers 27a-SB-6 of the 54th meeting of the Japan Society of Applied Physics, ‘Experimental evaluation of color image estimation method using multipoint spectrum measurements’).
FIG. 15 is a schematic diagram of the configuration of an imaging device provided with a miniature spectrometer of the related art. In the example of FIG. 15, an imaging device 70 includes an object lens 71, a mirror 72, an RGB image sensor 73, a miniature spectroscope 74, and an image processor 75. The RGB image sensor 73 acquires spatial information of a sample with more minute pixels. To detect highly precise changes in the spectral information, the miniature spectroscope 74 is configured with larger pixels than the RGB image sensor 73.
Light illuminated onto a sample 80 passes through the object lens 71 and is divided into two directions by the mirror 72. One beam of light divided by the mirror 72 is received by the RGB image sensor 73, and the other beam is received by the miniature spectroscope 74.
According to the above configuration, a multispectral imaging device can be configured with a simple configuration wherein spatial information is acquired by an RGB image sensor and color information is acquired by a miniature spectroscope.